1. Field of the Invention
The invention relates to target detection and tracking apparatus and is directed more particularly to an acoustic sensor assembly for detecting and tracking noise-producing and/or noise reflecting objects in an ocean environment.
2. Description of the Prior Art
Marine vessels, such as submarines and surface ships, are typically provided with acoustic sensor assemblies. In such assemblies a laser scanner is disposed and oriented so as to project a laser beam onto an after surface of an acoustic panel, the sensor being disposed and oriented so as to receive reflections of the laser beam off the acoustic panel and to transmit data from which a position of a sound generating source can be determined. An example of such an acoustic sensor assembly is shown and disclosed in U.S. Pat. No. 6,349,791.
Only the sound incident on a forward surface of the acoustic panel, that is, incoming sound from the water, is desired to be measured. The sound incident on the after side of the panel originates from inside the vessel (e.g. as a result of reflections) and is considered to be only “noise”. Because the system cannot distinguish between incoming sound and noise, there is a need to diminish or eliminate internal reflections that are otherwise detected.